The DJ known as Joey Flash spun music at bars and restaurants across the D.C. area and organized bartending competitions, a lifestyle that put him in touch with numerous women, his roommate said.

But as he was circulating in the late-night scene, Joseph M. Rivera also allegedly made videos and took photos of his sexual assaults on several unconscious women, according to Fairfax County police and a search warrant.

Rivera, 34, formerly of Four Mile Road in Alexandria, was arrested Tuesday night in Las Vegas and was awaiting extradition to Virginia to face charges of sexual assault in connection with the recordings, police said.

Jonas Mitchell, the roommate and a former friend of Rivera’s, said the DJ had ample contact with women and was personable. “He was the trusted guy to take them home,” Mitchell said.

When police interviewed Rivera, he told them that he had taken photos and videos of the women, authorities said in court papers.

Joseph Rivera

“All the victims appeared unconscious and, to this day, are unaware of the videos and photographs,” Detective Brian J. Byerson wrote in a search warrant filed May 13 in Fairfax County Circuit Court.

Some of the victims were subsequently interviewed, and they told investigators that they had not consented to the sex acts or to appearing in the videos, according to the search warrant. Police said other women that appear in the videos had not been identified.

Rivera told detectives that some of the videos were shot at his home at Stationhouse Court in Lorton — where he lived before Alexandria — and were stored on electronic devices, according to the search warrant. Rivera told police that the videos were created between November 2011 and December 2012, court papers say.

Authorities wouldn’t say where he encountered the women he is accused of sexually assaulting. It is also unclear how the women became unconscious before the alleged assaults. There is no indication that other people were involved, police said.

Rivera worked as a DJ at the BlackFinn restaurants in Bethesda and the District, A-Town Bar and Grill in Arlington County and Brion’s Grille in Fairfax, among other places, according to his Facebook page.

“We fired him because he never showed up,” said Sam Sumser, owner and bar manager of Brion’s.

Rivera has been charged with rape, aggravated sexual battery and animate sexual object penetration and two counts of unlawful filming, police said. The incidents may date back several years, they said.

Mitchell said Rivera disappeared after police began investigating the case. His Twitter account said he was scheduled to work as a DJ at a Las Vegas lounge the night he was arrested.

“People have dark secrets,” Mitchell said. “Unfortunately, his were very dark.”